Generally, various kinds of pedals, such as a rubber pedal or metallic rattrap type pedal, are well-known. The rattrap type pedal is used in a sports bicycle for cycle racing or cycle touring and has a pedal body comprising a pair of side plates between metallic inner and outer plates and a pedal shaft inserted into the inner and outer plates, the pedal body being supported on the pedal shaft through ball bearings, the side plates extending in parallel to the medal shaft. A front foot-bearing surface is provided at one side plate and a rear foot-bearing surface at the other.
The front and rear foot-bearing surfaces, which extend in parallel to the axis of the pedal shaft, are made flat, whereby a rider, when treading the front and rear foot-bearing surfaces, cannot fit the sole of his foot to just the foot-bearing surfaces. As a result, a treading force by his sole is transmitted to the pedal body resulting in poor transmitting efficiency.
The conventional pedal of the aforesaid type for a racing bicycle has been so constructed that the front and rear foot-bearing surfaces are curved to fit to just the sole of the rider's foot. The front and rear foot-bearing surfaces, however, are curved in equal radii of curvature, and do not mate with the sole of the rider's foot. Hence, the sole of the rider's foot, especially the toes thereof, do not just fit to the foot-bearing surfaces, whereby not only the treading force from the sole is not effectively transmitted to the pedal body but also the toes often are fatigued due to the concentration of a load applied locally to the toes.